Is it true that all test instruments have an accuracy rating?

The assertion that all test instruments have an accuracy rating is based on industry standards that generally require measuring instruments to provide some quantifiable indication of their accuracy. This accuracy rating is essential for ensuring the reliability and credibility of measurements taken by these instruments. Different standards, such as those established by organizations like ISO or ASTM, emphasize the importance of indicating accuracy so users can assess the quality and reliability of the measurement results.

Having an accuracy rating helps users make informed decisions about which instruments to use for specific applications and to compare the measurement capabilities of different instruments. It is critical for achieving consistent results in various fields, including manufacturing, laboratory testing, and process control. While it's acknowledged that there may be some very basic or non-professional instruments that lack a defined accuracy rating, the general expectation within professional and industrial contexts is that instruments should indeed convey their accuracy to ensure proper usage and reliability of measurements.